Coil form, and coils and transformers mounted thereto



Feb. 9, 1965 J. o. RENSKERS 3,169,234

con FORM, AND cons AND TRANSFORMERS MOUNTED THERETO Filed Aug. 17, 1959 IN V EN TOR.

Arrow visions are well known in the art, and invention ithas not been illustrated. V p v The top surface 22 ofuthe' skirt 20' is peripherally dimpied to provide a plurality ofjconical depressions Min United sates Parent of Filed Aug. 17, 1959, Ser. No. 834,367 4 (Iiairns. (Cl. 335--'192) My invention relates to an improved coilform, to a method for making coils and transformers and to the coils and transformers so made.

in printed circuitry as employed by the radio. and television industry, certain coilsand transformers are made in a spool-like form with terminals projecting from one end thereof which are inserted, often automatically, into appropriate receptacles in the printed circuit board. One significantproblern in the manufacture of coils and transformers for such insertion res'idesin the maintenance of a proper orientation and angularity of the terminals so as to be insertable accurately into their receptacles.

A major object of my invention, therefore,is the pro vision of a new and novel coil or transformer structure whereby the coil leads are accurately oriented and shaped at the conclusion of the manufacture thereof.

Another major object of my invention resides in the method of making such coils and transformers.

Yet another object of my invention lies in a new and novel coil or transformer structure for printed circuits and the like which is simple and inexpensive, wherein the coil or coils and the terminals thereof are supported firmly and accurately, and which is well suited to automatic manipulation.

Yet another object of my invention lies in a new and novel coil form for such coil or transformer structures whereby such method may be practiced and such coils and transformers made.

Other objects and advantages of my invention will be apparent from the following descriptions and drawings of which: i

FIG. 1 is a side elevation of a transformer incorporating my invention;

FIG. 2 is a side elevation of the FIG. 1; p

FIG. 3 is a side elevation of the inner, primary coil secondary coil of of FIG. 1 rotated from the showing of FIG. 1 to illustrate the offset of the leads thereof;

ice

the upper surface, there being six such depressions in the illustrated embodiment, and corresponding conical projections 26 on the undersidec28 of the skirt. Holes 30 are formed through the skirt in the bottoms of the conical depressions. The holes are proportioned to be somewhat larger than the coil leads which they are to contain. Slots 32 are formed in the edge 34 of the skirt to extend to each of the holes 30. The slots'are desirably formed to extend at a substantial angle away from the radial with respect to the skirt to meet the holes 30 at points spaced inwardly from the outermost edges thereof. 7

The coils of the described tranformer are illustrated in FIGS. 2 and 3. FIG. 2 shows the secondary coil which is the outer coil of FIG. 1. This consists of a helical winding 36 of insulated wire with the bottom lead 38 thereof bent through a right angle to extend downward from the coil and the upper lead 49 bent'likewise through a right angle to extend down outside the coil 36 and project th'erebelow parallel to the axis of the coil. The leads may be ofiset outwardly as needed to enter the appropriate holes 30 in the skirt 22. The primary coil 14 of FIG. 3 includes a helical wind- 1 ing 42 of smaller radius than the radius of the secondary FIG. 4 is a bottom planview of the coil form of PEG. 1, shown with-the coil leads projecting therefrom; FIG. 5 is a fragmentary vertical section through the coilform taken substantially along the line 55 of Pro. 4;

PEG. 6 is a view similar to the right hand portion. of

FIG. 5, showing, however, a coil lead anchored in the I I 56 having a molten tinning composition 58 therein. The insulation of the wire used in coil manufacture is generallythermosplastic, and the binning dip strips back theallyof acoil form 12, aprimary coil l4 and a secondary collie surrounding andoverlying the primary coil 14;

The co'il' form i2 is made ofa thermoplastic insulating.

material such as nylon, polyethylene and the like, ,and includes a tubular pest 1S which extends through the coils and an annular skirt or. flange 20 extending aboutithe lower end thereof. The post; 13 may have internal procoil l o so that it may be inserted within the secondary coil, and of sufiicient inside diameter to fit over post 18 of the coil form. The lowermost lead 44 of the primary'coil extends outwardly as at 46 from the coil and then downward as at 48. The upper lead 59 or" the coil proiects outwardly from the coil as at 52 and extends downwardly as at 54 to extend below the helix 42. The outward extensions 46 and 52. of the two leads is for the purpose of spacing the leads properly for reception in the holes 36 and the outward extension 52 is for the additional purpose of permitting the reception of the secondary coil 16 between the helix 42 of the primary coil 14 and the upper lead thereof 50.

The assembly of these components is believed evident from their description. The primary coil 14 is inserted in the secondary coil 16 and the two assembled coils dropped over post 18 of the coilforrn 12. The down wardly projecting leads 38, 40, 44 and 50 may be guided into certain pro-arranged holes 30 in skirt 20 so that a" particular orientation of leads, either absolute or relative, pertains according to the coil users' specifications. Should it be the case that the leads are not axial oar properlyspaced from the axis of'thecoil or oriented inaccurately for the direct insertion into holes 30, as will most likely be the situation, the'leads may be inserted into the holes 3subsequent to the deposit of the coils on the post 18 and the seating thereof against skirt 26 by snapping the leads through slots 32 into'the appropriate holes'3il.

A usual part of the manufacture of such coils or transformers involves. tinning the leads thereof. This is achieved by dipping the leads in atinning bath as illus trated 'inFlgG. 7. The tinning bath is simply a reoeptacle insulation with immersion of the leads into the bath.

A. part of my invention resides in'dipping accurately the leads. of the assembled but not yet" completed transformer as described above into the tinning bath sothat thesurface of the tinning bath-touches theconicalv downward projections 26 encircling the leads in'holes 30 and the thermoplastic material of which the coil form is made vision for adjustably mountingf a core, but as,. such proplayno part in my:

melts and floats on the surface of the bath into the holes fill to close about theQleads as illustrated in FIG, 6.5 Re

movalof the leads andsubsequentcooling of the-transk former. skirtymaterial'then' anchors the coils to thecoil form by theirleadsand insures a precise angular rela- I Patented Feb. a, less tion of the leads and a relatively exact cylindrical extension thereof from the base of the coil form well suited for insert-ion in a printed circuit board. The fioated plastic of the projections bonds successfully to bare wire, but particularly Well to the insulation on the wire.

Upon cooling, the melted plastic of the projections provides an embedrnent which is a major means of securing the coil to the form. Possibly a seal may be achieved without actual contact of the projections with the surface. The projections will soften and flow somewhat from the radiated heat of the bath if brought very nearly into contact and from the conduction-heated leads extending therethrough and the stripped insulation may join the projection ends to contribute the seal.

Since the leads are anchored in the coil form skirt close to their ends the leads have substantial stiffness and are well able to withstand bending forces which may arise in subsequent handling. Should the leads be bent in handling they may easily be straightened again without destroying the seal between the leads and the coil form skirt.

I have tried forming the slots 32 radially in the skirt and leading directly into the holes and have had some success with such structure but I find an occasional tendency of the leads to spring back out of the skirt through such slots in the tinning and sealing process. In the tinning process I find that the slots, particularly the non-radial slots shown, usually heal themselves and flow closed.

It will be noted in FIG. 6 that the conical downward extensions 26 are not completely leveled in the tinning dip but rather, as may be seen in FIG. 1 the leads extend from what may be considered small bosses 60, the residues of the projections 26. This is a characteristic deliberately sought and controlled by the depth of the immersion of the transformer leads into the tinning bath. In printed circuits it is desirable for ventilation and the avoidance of condensation between the mounting board and attached components or circuit elements that such elements be spaced slightly above the surface of the mounting boards, and the radial bosses 60 meet excellently this spacing function.

It is believed that the structure of the coil illustrated in FIG. 8 will be readily understood from the foregoing description of the transformer. The coil 61 is illustrated as being constructed on the same coil form 62 described in conjunction with the transformer. In this case, a single helical winding 64 is placed on the tubular post 66 of the coil form to abut at its lower end against skirt 68 of the form. The free ends 7i) and 72 of the winding are passed through the desired holes in the coil form skirt either directly or by forcing them through slots identical with slots 32 of FIG. 4. Free end or lead 72. constitutes the upper free end of the winding 64 and is carried down the outside of the winding to extend below the coil form skirt as illustrated. The leads of the assembled winding and form are then tinned as described before to seal the conical projections identical with projections 26 of the transformer structure, about the leads 76 and '72 and so create the bosses 74.

It will be evident from the foregoing description that my invention is capable of many applications and likewise that many variations and differences in structure will readily present themselves to those skilled in the art.

The coil form of'rny invention is not restricted to the six holes described and many holes may be provided to accommodate electric or electronic components having a considerably greater number of leads. Likewise it will be appreciated that my coil form and method need not be specifically limited to the manufacture of trans formers and coils but that many other areas of application will suggest themselves.

independently by dipping the ends of the projections in a bath of any appropriate fluid heavy enough to cause a floating of the melted or softened thermo-plastic and hot enough to cause the requisite softening or melting. Thus where tinning of the leads may not be required, separate dip will be employed to make the seal. I therefore desire that my invention be regarded as being limited only as set forth in the following claims.

I ciaim:

1. A circuit component comprising a coil form having a post and an insulating skirt at one end thereof made of a thermoplastic material having the general characteristics of nylon and polyethylene including having a melting point below the temperature of a tinning bath, said skirt having integral bosses on that side thereof away from said post, and an electrical winding about said post having free ends extending through said bosses and beyond said skirt, the portions of the ends of said winding beyond said skirt being tinned and the portions of said ends within said skirt being embedded in a solidified melt of said bosses, said embedment of said ends being at least a major means of securing said winding to said form.

2. A coil form comprising a post, a thermoplastic insulating skirt about said post adjacent the lower end thereof, said skirt having a plurality of projections from the lower surface thereof and a plurality of apertures therethrough centered in said projections, and slots extending from the periphery of said skirt at a substantial angle to a radial direction and intercepting said apertures at a point spaced from the outermost edges thereof.

3. A circuit component comprising a coil form having a post, an electrical winding about said post, an insulating. flange on said post made of a thermoplastic material having the general characteristics of nylon and polyethylene including having a melting point below the temperature of a tinniug bath, at least one end of said Winding extending parallel to the axis of said coil and through said flange, said flange including an integral boss on the surface thereof remote from said winding, said end extending centrally through said boss, the portion of said end Within said boss being embedded in a solidified melt of said boss, said embedment of said end being at least a major means of securing said winding to said form.

4. A circuit component comprising a coil form having a post and an insulating skirt at one end thereof made of a thermoplastic material having the general characteristics of nylon and polyethylene including having a melting point below the temperature of a tinning bath, and an electrical winding about said post and adjacent one face of said skirt at one end thereof, the free ends of said winding extending through and beyond said skirt, said skirt including integral bosses on the side thereof remote from said winding, said ends extending through said bosses, the portions of said ends within said skirt being embedded in a solidified melt of said skirt, said I embedment of said ends being at least a major means of securing said winding to said form.

References Cited by the Examiner UNITED STATES PATENTS 2,412,836 12/46 Rose 29-15555 2,867,894 1/59 Hill 29-15556 2,879,584 3/59 Skobel 29 155.56 2,889,497 6/59 Wolf et al 336-l92 X 2,889,524 6/59 Schmitz 336-l92 2,918,640 12/59 Higgs 336-l92 X 2,929,132 3/60 Wohlhieter 336l92 X 2,941,172 6/60 Sutton 336136X LARAMIE E. ASKIN, Primary Examiner.

ORISL. RADER, MILTON 0. HIRSHFIELD, JGHN F.

BURNS, Examiners. 

1. A CIRCUIT COMPONENT COMPRISING A COIL FORM HAVING A POST AND AN INSULATING SKIRT AT ONE END THEREOF MADE OF A THERMOPLASTIC MATERIAL HAVING THE GENERAL CHARACTERISTICS OF NYLON AND POLYETHYLENE INCLUDING HAVING A MELTING POINT BELOW THE TEMPERATURE OF A TINNING BATH, SAID SKIRT HAVING INTEGRAL BOSSES ON THAT SIDE THEREOF AWAY FROM SAID POST, AND AN ELECTRICAL WINDING ABOUT SAID POST HAVING FREE ENDS EXTENDING THROUGH SAID BOSSES AND BEYOND SAID SKIRT, THE PORTIONS OF THE ENDS OF SAID WINDING BEYOND SAID SKIRT BEING TINNED AND THE PORTIONS OF SAID ENDS WITHIN SAID SKIRT BEING EMBEDDED IN A SOLIDIFIED MELT OF SAID BOSSES, SAID EMBEDMENT OF SAID ENDS BEING AT LEAST A MAJOR MEANS OF SECURING SAID WINDING TO SAID FORM. 